Clisthenes did not limit himself to this change in the constituent bodies--he increased the total number of the constituents; new citizens were made--aliens were admitted--and it is supposed by some, though upon rather vague authorities, that several slaves were enfranchised. It was not enough, however, to augment the number of the people, it was equally necessary to prevent the ascension of a single man. Encouraged by the example in other states of Greece, forewarned by the tyranny of Pisistratus, Clisthenes introduced the institution of the Ostracism [248]. Probably about the same period, the mode of election to public office generally was altered from the public vote to the secret lot [249]. It is evident that these changes, whether salutary or pernicious, were not wanton or uncalled for. The previous constitution had not sufficed to protect the republic from a tyranny: something deficient in the machinery of Solon's legislation had for half a century frustrated its practical intentions. A change was, therefore, necessary to the existence of the free state; and the care with which that change was directed towards the diminution of the aristocratic influence, is in itself a proof that such influence had been the shelter of the defeated tyranny. The Athenians themselves always considered the innovations of Clisthenes but as the natural development of the popular institutions of Solon; and that decisive and energetic noble seems indeed to have been one of those rude but serviceable instruments by which a more practical and perfect action is often wrought out from the incompleted theories of greater statesmen.